View Full Version : Thermostats and thermo switches

16th December 2005, 08:54
A burst of paranoia while I was balancing the carbs caused me to pull the thermostat, thermo switch (for the fan) and temp sensor (for the warning light) out of the bike to test them.
I haven't tested the sensor for the warning light, but the thermostat and thermo switch seem ok.
The thermo switch turns on at 108C and turns off at 101C. It has "on at 105 stamped on the side.
The thermostat just starts to move at 85C and you can start to see through the opening at about 88C. It has 82C marked on it.

Both are pretty close to the marked values, so I'm guessing they're ok?

How do you tell if a thermostat/thermoswitch is worn out? Is it a case of either working or not working, or is there a rule of thumb as to how far from the marked temperature they can opperate?

(I'm pretty sure the digital temperature gauge I used is accurate, I tested in in some boiling water and it indicated 99.8C)

16th December 2005, 09:21
The thermostat will have a lift (mm) figure for given tempertures.. ie.. over 8mm at 95C for a 82C TL1000 thermostat,which should be opening at 80 to 84C.The opening readings you got seem a little off for the 82C rating ... the fan sensor sounds fine,if it has a temp sensor they are normally checked by set resistances at a given temperture.

16th December 2005, 10:02
from the info you have given us it souns correct IMHO i would probaly get them tested properly though ;)

16th December 2005, 10:40
That's what Erik does - test things properly,he'll spend 3 days making a test rig for a 2 minute test.The thermostat will behave differently in the bike than in a cup of water,so don't expect it to be exact - one trick we do is to suspend it in the water with a wire (I use my thermocouple wire),it will drop off the wire when it opens,easy to see and check the temp.Your temp sensor only does the light,so it may just switch at a value - but to test temp sensors I use a graphing meter and will show the gradual change in resistance as the water heats up,and any drop outs are obvious....this is important on modern cars as the computer responds to these glitches.

16th December 2005, 10:41
from the info you have given us it souns correct IMHO i would probaly get them tested properly though ;)

It sounds like he is doing a great job so far..it is inspiring to see younger people taking the time and interest to really get into the mechanics of things :niceone: